Quote:
Originally Posted by Onkel Neal
Wait, what? Grind the exhaust valve seats? That must have a very different meaning from grinding valve seats on an automotive engine...  You must be referring to the exhaust valves in the line, not the heads, right? |
There were flapper valve seats in the external and internal exhaust vents. Carbon would form on them and prevent a good seal when diving, and so periodically they needed to be ground. The external ones had pneumatic motors that would do it, but the internal ones you had to do by hand. You’d slap a big ratchet handle onto this male end here and crank back and forth for a while to unseat the carbon. Rinse and repeat on the other engine 4-6 hours later. Buchheim had the pleasure of doing this and describes it in Das Boot when he stands a diesel watch.
Some early boats were lost due to this design flaw.